AP BIOLOGY

PHOTOSYNTHESIS

LIGHT DEPENDENT REACTIONS

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
Where does light reactions take place?
A
Stroma
B
Thylakoid
C
Cytoplasm
Explanation: 

Detailed explanation-1: -The light reaction takes place in the thylakoid discs. There, water (H20) is oxidized, and oxygen (O2) is released. The electrons freed up from water are transfered to ATP and NADPH. The dark reaction occurs outside of the thylakoids.

Detailed explanation-2: -In plants, the light reactions take place in the thylakoid membranes of organelles called chloroplasts. Photosystems, large complexes of proteins and pigments (light-absorbing molecules) that are optimized to harvest light, play a key role in the light reactions.

Detailed explanation-3: -The light-dependent reactions of photosynthesis take place within the thylakoids. These reactions occur when the pigment chlorophyll, located within the thylakoid membranes, captures energy from the sun (photons) to initiate the breakdown of water molecules.

Detailed explanation-4: -The chloroplast is involved in both stages of photosynthesis. The light reactions take place in the thylakoid. There, water (H2O) is oxidized, and oxygen (O2) is released. The electrons that freed from the water are transferred to ATP and NADPH.

Detailed explanation-5: -The membrane system is responsible for trapping solar energy and synthesis of ATP and NADPH while stroma has enzymes for reduction of carbon dioxide into carbohydrates. > So light reaction occurs in the granum while dark reaction occurs in the stroma of the chloroplast.

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